Bowcott will be responsible for the day-to-day running of the planning department and report to Richard Huntington, the director of strategy. She replaces Rachel Lawlan.
Before joining Havas Worldwide in May last year, Bowcott was the planning director at Droga5 in Sydney. She has also worked at Bartle Bogle Hegarty.
Huntington said: "Lisa combines imagination, audacity and rigour – the perfect combination to lead an increasingly potent planning department at Saatchi & Saatchi."
The agency has also made a number of other hires. It has appointed Simon Humphris, a global client director at Iris Worldwide, as the managing partner and head of account management. He will report to Magnus Djaba, the chief executive, and Katrien De Bauw, the chief operating officer.
Zoe Bell, a former head of TV production at Mother, joins as the head of integrated film. Bell, who is a former vice-chairman of the British Arrows, moves from the headhunter Grace Blue.